The active corrosion performance of silane coating treated by praseodymium encapsulated with halloysite nanotubes

In this study, the effect of active corrosion protection of silane coating containing praseodymium (Pr) encapsulated in the internal lumen of halloysite nanotube (hal) was investigated. First, For better loading process, the inner diameter of hal after 48 h of acid-modification was increased, then it was encapsulated using a urea-formaldehyde shell to optimize the inhibitor for a long time. The structure and morphology of particles were studied using SEM, HRTEM and FESEM tests. The encapsulated hal was dispersed in the silane hybrid matrix and deposited it by dipping on the surface of an AZ31 magnesium alloy. The curing process of silane coatings and encapsulated silane in an oven at 110 °C for 2 h was investigated by FT-IR test and physical surface properties of coated substrate were investigated by water contact angle test. Finally, EIS and polarization tests were performed for blank substrate, with silane coating and silane coating containing capsules. The results indicate an increase in surface polarization resistance for coatings containing capsules, which prevents electrolyte entry by creating a protective coating. The substrates with silane containing capsules showed the highest corrosion protection after immersion in a 3.5 % NaCl solution. To further study of the release of inhibitors at the scratch site, the FESEM-EDX, MAP test showed that Pr prevents the entry of electrolyte into the metal-coating by creating a protective film of Pr oxides/hydroxides.